Circuit-controller.



S.C ABUT. CIRCUIT CONTROLLER. APPLIUATION FILED NOV 10, 1908.

91 7,749. Patented lpiz 33, 2909.

S'. CABQT. CIRCUIT CONTROLLER. APPLICATION FILED NOV. 10, 1908.

917,749. Patented Apr. 13, 1909.

2 SHEETS-SHEET 2.

SEWALL CABOT, OF BROOKLINE, MASSACHUSETTS.

CIR-GUIT-CONTROLLER.

Specification of Letters Patent.

satelites April-ia, ieee.

Application led November 10, 1908. Serial No. L161,926.

To all whom it may concern: Be it known that l, SEWALL CABONT, acitizen of the United States, and a resident of,V Brookline, in the county of Norfolk and State' of Massachusetts, have invented a new and useful Improvement in Circuit-Controllers, of which the following is a speciiication.

,My invention relates to circuit-controllers and more especially to devices for controlling the operation of sonorous or persistently-os cillating circuits which are employed in space telegraphy and other arts for creating high frequency electrical oscillations. I Heretofore the device most commonly employed for controlling suoli circuits has been -the spark-gap, consisting of two separatedelectrodes which are either stationary or relatively movable. When the electrical potential oithe condenser reaches a suiiicient value to cause a disruptive discharge at, the gap, the circuit becomes closed throughl a path of metal vapor between the electrodes allowin@ it to oscillate until the electrical energy lias been dissipated in radiation or in supplying heat to the spark. gap. it has long been recognized that a considerableamount of energy is lost in supplying heat to the spark-gap and that also under certain conditions it becomes di'l'licult to clear away the metal vaporl between successive wave trains thus causing the potential at' whichdisruptive discharge takes place to vary and impairing the quali-ty of the sound of the rslpark Ias heard at the receiving system.

he production of this' vapor furthermore at high powers also manifests itself vas a very loud and disagreeable noise. It has lfurther'- more long been recognized that condensers of small ca acity and high dielectric strength might be charged to a very high potential by breaking a circuit carrying a unidirectional current iowing in an inductance provided it is possible to give the point of interruption of such circuit a dielectric stren th sufiicient to withstand said potential wit iin a length of time very short compared -to the time re quired to charge said condenser to 'said potential, the xtime re uired to charge said condenser being' equa to one-quarter of the time period-oil the circuit `including` said capacity and inductance.

The object of my invention is to provide means for disturbing the electrical equilibrium of a circuit including inductance and capacf ity more effectively than by the use of the spark-gap or circuit-controllers which have heretofore been used for this purpose.

.In carrying out my invention I may ern ploy a circuit-controller having a plurality of sets of relatively movable electrodes and power-operated means forcreating such relative 'movement, each set of electrodes being so4 lserially subdivided that, without resorting to excessively high peripheral velocities, the path which includes said electrodes may periodically be changed from one which is 'insulating for very high potentials to one which is substantially metallically-continu ous, within a period of time which is suilicientlyshort to minimize the spark-gap losses aforesaid during-the effective radiation of energy from thecircuit including said electrodes and which preferably is comparable withthe time period of said circuit. l

may further employ said circuit-controller,

having its electrodes sosubdivided and relatively movable, for the purpose of charging the. condenser of a sonorous circuit directly from-a source of constant and relatively low potential through an inductance, thereby obviating vthe necessity of employing an inductionv coil, or an alternating current source with 4high potentialt'ransformer, for this pur pose.

My invention may best be understood by having reference to the drawings which accompanyl and form a part of the present specification and which represent Atwo are rangements of apparatus and systems of circuits' embodying my invention.

In the drawings, Figure 1 represents partly in diagramand partly in elevation one enibodiment of' my invention used Yin a space transmitting system in which a source of alternating current is employed, and Fig. 2 represents a similar view cfa modification in whicha source of dii'ectcurrent is used.

conductor connected to earth at E and includingthe secondary winding l, of a transfcrmer,'the primary l, of which forms a part of the sonorous ci'rcuitincludin'g the con .y

denser@ and the dischargcr hereinafter described.: It will be understood of course that the sonorous circuit may be associated vwith said elevated conductor in any suitable manner.

i A represents-an alternating current generatoror other suitable source of alternating current having its leads connected to the key K and the primary l1 of the high potential transformer, the secondary IZ of which is j connected with the sonorous circuit at the CTI the same in adjusted position.

points a and y. ln the present instance, the circuit-controller' or discharger is connected with the sonorous circuit at the points and y, and consists essentially in a rotating niember 2, which l shall term the rotor, carrying the two series of conducting members a b insulated from each 'other and also the two series of conducting members c/ b likewise insulated from each other and arranged dia metrically opposite the corresonding members a b. The rotor should be driven at a speed equal to thenuinbei' ofcycles produced by the'alternator A and thisaiimay be conveniently accomplished by mounting saidA rotor on the shaft 3 of the alternator.

' 8 8 and 9 9 are rocker arms carrying the rods l0 and ll respectively, which maybe of insulating material and which in turn carry the two series of conducting members c, d, respectively. The rocker arms preferably are arranged to be adjusted about the periphery of the rotor and this may be accomplished by securing them to the collars 5 6 and 5 6 supported by the bearings 4 4 of the shaft 3 and by providing the usual means such as the handles 7 7 for turning the rocker arms about said bearings and locking As shown, the alternator and the journal 4 may be supported upon a common base 1. The mem- Jers a b c and d are arranged as shown, so that, when one set of moving members, such as that shown at a, passes between a set of stationary members such as that shown at c, the other set of moving members will occupy a correspoi'iding position with respect to the other set of stationary members, so that there will be formed between the points a:

and y av path of practically-negligible re-` sistance by way ofthe ieXible conductor 12l which connects the stationary members c d which are nearest the alternator.

Assuming that the rotor is rotating in a .clockwise direction as viewed from ,the alternator end, so that the series of members a is approaching the series c, it will be seen that by the proper adjustment ofthe rocker arms and the proper s acing of the several series, a number 'of sma gaps will be inserted in the path 12 y, the total dielectric strength of which willprevent the disruptive discharge of the condenser C until the potential of the same has risen to' its maximum value. When the potential of the condenser is a maximum,v by the adjustments above referred to, the total dielectric strength of said -gaps may be made just sufcient to ermit the discharge ofthe condenser across t e discharger at any given position of the series 'a and As the rotor continues its rotation and the several gaps between the series a and the series c and also between the series ,series of moving mem ers from its coperat-' ing series of stationary members has become very small. lf the rotor is given' a fairly large peripheral velocity, it will be possible to make the interval of time between the position of the series c7 2),' at which the rst disruptive discharge of the condenser occursv and theposition of said series at which the circuit becomes practically metallically-continuous as small as lwe please, so that such time interval will be comparable withthe time of a single oscillation of the sonorous circuit, or, in other words, with the time period of said. circuit.

V-In wireless engineering practice only a small part of the total energy of the wave train is dissipated in the first oscillation and the above means allows the spark-gap to be withdrawn from the circuit during the greater portion of time that radiation is taking place, thereby nearly eliminating spark-gap losses and the disagreeable noise incident to forming large masses of metal vapor. It furthermore prevents the disf charge from taking' place except when the potential of the condenser is at a maximum in the alternating current cycle thusv insuring an equal energy in each succeeding wave train and rendering the sound of the spark smooth at the receiving station. ,By swinging the rocker-arms through an angle of 180 degrees and' noticing at what point the potential of the elevated conductor reaches a maximum, this oint in the alternating current cycle may e adjusted for.

ln order'to more fully disclose my invention I will now proceed to show' by ay numerical eXample using values in' common use how the number of electrodes and' circumference of the rotor may be determined.. v Let us assume that the alternating current supply is 60 cycles per second and that the rotor is therefore run at160'rev'olutions per second or 3,600 to the minute; In order not to get into any construction difficulties due to centrifugal force let usmake the rotor only l meter in circumference corresponding rotor have approached sufficiently near the rows of brushes to allow a disruptive diset us assume the wave length lsecond after the conducting elements of the. j

a rent cycle.

y ing synchronously with'alternating` current,

f tion shown in Fig. 2, be made to open an eleccharge. lith a peripheral speed of me- I ters these elements would move a distance ot i .2 mnrdurine` this time. Vale should provide l brushes and conducting elements insufficient number to produce the requisite number of .2 mm. gaps in series to prevent disruptive discharge when vthe maximum potential on the condensers is applied. rthe potential necessary to cause a disruptive discharge across .2 mm. of air (Gray, Physical Review 1898, Vol. ll', p. 199) is about 1000 volts and we should therefore provide for at least 32 gaps of .2 min. if the maximum potential on the condenser were 32,000 volts. This number of raps would be obtained by the use of 9 brushes on each rod and comluctingl elements in each row of the rotor.

lt is obvious that should a source ol" constant high potential be available., the alternating current transformer might be dispensed with together with the necessity of adjusting thc rocker'arm to allow discharge of the condenser only at the oint of maximum potential during the a ternating curln this case the rotor could be driven at any desired speed by a direct current motor or other means and the speed of rotation would determine the time period between successive wave trains. The source oi constant high potential should include some inductance to limit the flow oi current during; the instant of discharge. Yit isalso obvious lo *hose versed in the art that a portion of i the surface ot the rotor could be used as a commutator to change condensers from parallel to series connection allowing,A them to charge in parallel from constant low potential and to discharge in series. It is also obvious that in the case of the rotor revolvthe controlling key may be connected in the high potential circuit disclosed by me in U. S. Patent 884,070, dated April 7, i908, so as to allow it to only interrupt the circuit at n the instant in the cycle of zero current `tlow thus preventinfk-g wear due to sparking.

Passing now to the second embodimentof my invention, it will be scenthat the device shown in lfigj. l can by the slight modilicatric circuit carryine a direct current and in- I sulate the opening; to withstand a very high i potential within a space of time comparable l with l/300,G0O of a second. The modical tionin question consists in arranging the 1 i l I 1 l rotor with conducti members a e insulated l'roin each otn'erA and extending as shown in the present instance around 315 degrees et' arc, and in providing' two independent and relatively movable sets of conductingr members c c' and d d', which perform the function of making a conducting path between the insulated conducting members of the rfitor when either set isvin contact'fliere wi fi.. By varying the angular separatinn fbel tween the set of electrodes or conducting` members c fl', one of which may be mounted. on the Vlixed supports 8 8 and the other on thc rocker-arms 9 Q', the interval of time during each revolution'that the circuit remains open can be varied. This interval would be Zero it the brushes were 4-5 degrees apart and would increase to a maximum as the set of conducting members on the rocker-arm was moved ytoward the 'fixed set. YWith the circuit-controller thus modified it would'be possible to operate the wireless transmitting` circuit shown in Fig. 1 with a low voltage constant potential source without employing an induction coil. To do this an inductance L should be connected in series with the source of constant potential G and the terminals of this source connected to the points fc, y and to these points should also be connected the modified circuitcontroller shown in Fig. 2.

The numerical values of various elements of the system shouldbe so adjusted and proportioned that they bearthe following relations: Let L, be the value of the inductance in the oscillation circuit in henries, C, the' value of the capacity in the oscillation circuit in tarads, V, the maximum potential in volts to which the condenser in the oscillation circuit is charged, W', the power consumed in watts, inthe oscillation circuit, L, the inductance in the constant potential circuit in henries, R, the resistance of the const-ant potential circuit in ohms, E, the potential of the constant potential circuit in volts, i, the maximum current in the constant potential circuit in amperes, Tx, the time of one oscill ation in seconds, T2, the time of one revolution of the rotor in seconds, T3, the time during which the circuit through the rotor remains open in seconds, p, Athe peripheral velocity of the rotor. in meters per second, N, the number of gaps in series in the circuit c l2 y or x 12 y through the rotor.

TFM/IT ce T %cv2 2 1/gLrl (C) E ,elif l-,R l1; i, (d)

T I fa/@Q V i T 2 c k 1000 to lfilquation (a) determines the time. period lli) of the sonoious circuit and therefore the wave-length of the radiated wave.

Equation (b) determines the energy consumed in the sonorous circuit in one second. Equation (c) sliowsvthe relation of the kinetic energy .stored in the magnetic field of the inductance or inductances L in the constant potential circuit to the potential energy stored in the condenser C of the oscillation circuit. 2 2

Equation (d) determines the value 'of current in the constant -potential -circuit ywith vgiven values of L, E and R, at the end of time T2. It will be understood that the' time represented by T2 should be T2-T2,

but as T3 is negligibly small compared to T2,

-numerical value or Y a sufficiently close a proXiination is obtained by using the va ue of T2.

Equation (e) shows the relation which is necessary in order that the wave train. may b`e started at the instant whenl the energy is all stored in the oscillating circuit.

lEquation (f) determines the number of gaps in series in the circuit through the rotor.

Equation (g) determines the peripheral speed of the rotor whereby atravel of'.2 mm of the conducting elements thereon may cause the discharge path to change from the condition of insulating at the voltage V to perfectly conducting at the endof the first oscillation.

In designing a wireless telegraph trans- 'mitting system certain quantities are usually specified in advance. These are wavelength, power absorbed by the oscillation circuit, spark frequency, voltage of constant low' potential source, and percentage ehiciency of the system, and power factor in the supply source.

' constant potential circuitv shall have the co1- rect value of inductance L and resistance R to cause it to deliverenergy to the oscillating circuit at the speciiied rate and within the specified efficiency and power factor.

The eficiency and power `factor of the system is fixed by assigning a numerical value to the fraction This detern'iinesl the. I

For values of this fraction varying from l to .5 the eifhciency'varies from approximately '50% to 75% respectively and the poweiq factor from approximately 90% to 88% respectively.

Tt now becomes necessary to determine 'the values of R and L to give the specified By a simultaneous solution of formulas (c), (c), (d'and (7L) it is possible to deduce MR2 R-ewk (i) f 2Wk? (y) By applying calculus to'equation (d) it is possible to deduce the value of the heat losses in the resistance of the constant low potential circuit QWCQL z i R m Uf) also the cilective value of the current in this circuit ,dan Y Em n d) From equation (le) is obtained the expressien W 1mi Vel-2R nlr l+ Y -m (m) giving the percentage ol' eliiciency of the System.

From equation (l) is obtained 4the expreslSion lll@ i@ m 52mg E@ 21a/a (n) e giving the power factor of the supply circuit, To illustrate the method of calculation more fully I will work out a practical case numerically using values which may be said to be average in working wireless telegraph `installations to-day.

The specified quantities are as follows; T,=,oeo0o3e YV :410000 T2= .Gl E l0() RT., I 1Y-=r=-5 (corresponding to 73% elli- J cicncy.)

The calculated values are as follows:

C :.1 mfd.:.0()00001 (my) El'liciency.: 78.3% (n.) Power factor :89%

The above values are approximate only within engineering accuracy.

The operation of this system may be eX- plained in the following manner: l/Vhen the rotor lirst closes the circuit, current supplied .from the constant potential source starts to flow through the inductance L and constantly increasesreaching avalue l given in equation (d) w' en the rotor has made almost a complete revolution. At this instant the circuit through the rotor is opened and becomes the electrical equivalent of a closed sonorous circuit of inductance li and capacity C in a condition where the energy 1, L i2 is all stored in the magnetic iield. live know from thetheory of the sonerous circuit that, after a space of time T, equal to one quarter of a single complete oscillation (equation e), this magnetic iield willI have completely collapsed and all of the energy will be stored in the condenser (l and have a value of (l V2. At this instant' the circuit is again made through the rotor, the energy in the condenser makes an oscillatory discharge through the small inductance L, and is dissipated by radiation, while current commences to low again in the coil and the cycle is complete. The time necessary for radiation to take place is very small compared. with the time of one revolution of the rotor and it is advisable to proportion the values of L and C so that T3 corresponds tobonly a small angularmovement of the rotor. This allows the inductance li to be accumulating energy during,T the largest possible amount of the total time andv renders it possible to use a minimum value of constant electro? motive force for a given number of watts output.

I t is obvious from the above that by the use of an inductancc, condenser an d constant low potential source in combination. with ay circuit-controller of the nature last dcseribml, We may produce high potential disruptive discharges of any desired length. llduations (c) (d) and (c) live us all data required for calculating values necessary to produce any desired value ol,lv V. Care should be taken to subdivide the rotor so as to produce insulating' gaps in sufficient number to with- 4 stand the desired potentialV within a space ottime shorter than that given in equation (c). The electrodes between which disruptive vdischarge is desired should be connected across the condenser C and should have a breakdown Y potential value anythingl less than V.

It will be seen that by the employment of my invention as herein set forth l am enabled to produce jump sparks for explosive engines without the use of vibrators or induction coils. Furthermore l am enabled to provide apparatus for use in therapeutic and radiographic work wherein the induction coils may be improved and simplified by the omission of the iron core and by a considerable reduction in the amount of wire required. l. may also further simplify such induction coil by omitting' the usual condenser, because, as pointed out by lllheatstone, it the primary current of an induction coil vcould be 'interrupted Within a su'lliciently short time interval, the use ol" a ccndenser might be dispensed with and the 'secondary potential increased, since 1t is dependent on the rapidity with which the magnetic i'ield collapses and it is obvious that the above described circnit-controller can be employed lor this purpose.

lt has lone' been recognized that an im mense advantage would accrue in wireless telegraph engim-:ering il it were possible to completely eliminate the resistance of the spark gap. lt has also long been recognized that much greater e'llciency could be ob-A tained m converting low potential to high potential by breaking' an inductive circuit in which current was l'lowing` it this break could be made with su'llicient rapidity to prevent sparking.v That neither of these two advantages has been made use of to my knowledge con'nnercially is probably due to the apparent impossibility without resorting" to prohibltory velocities of constructing* a path which would in a Asulliciently short interval of time change between the conditions of perfectly insulatingr forl high potentials and perfectly conducting.

Having shown how the principle of serial subdivision may be made use ol to reduce the rapidity of motion necessary to accomplish these results, I claim:

l. A eircuit-controller serially connected in a sonorous circuit and having a plurality olz sets ot serially subdivided electrodes and power-o]erated means lor creating relative movement between the same.

2. n circuit-controller serially connected in a sonorous circuit and having a plurality ot sets ot' serially-subdivided electrodes and means l'or creatingr relative movement between the same, the said sets of electrodes beineso constructed and arranged that the gaps between the same are practically closed and said circuit yrendered substantially nietallically-contmuous in an interval oi time after the first discharge oi the condenser in tween-the same, the said sets of electrodesbeing so constructed and arranged that the;

gaps between the same are practically closed and said circuit rendered substantially metallically-,continuous in. an interval of time after the first discharge of the condenser in said circuit shorter than the duration of the eective radiation of energy from said cir-V cuit.

in a sonorous circuit and having a plurality of sets of serially-subdivided electrodes and means for creating relative movement be-t tweenthe same, the said setsof electrodes being so constructed and arranged that the gaps between the same are practically closed and' said circuit rendered. substantially metallically-continuous 1 in van interval of time after the iirst dischar e of the condenser in said circuit comparab e with the time period oi said circuit.

5. A circuit-controllerserially connected in a sonorous .circuitand having 'a set of stan tionary serially-subdivided electrodes, a set of movable serially-subdivided electrodes,

and power-operated means for creating relajshorter than one-quarter of the time period tive movement between the same.

(LA circuit-controller serially connected in a sonorous circuitand having a set of sta` tionary seriallyfsu'bdivided electrodes7 aset of movable seriallysubdivided electrodes,-v

and means for creating relative movement between the same, said sets oi electrodes bein said circuit suiiiciently short to minimize ing so constructed and arranged that the gaps between the same are practically closed and said circuit rendered substantially metallicallycontinuous in an interval` of time after the iirst discharge oi the condenser spark-gap losses'during the eilecti've radiation of energy fromsaid circuit.

7. A circuit-controller serially connected in a sonorous circuit and having a set of stationary serially-subdivided electrodes, a set of movable serially-subdivided electrodes, and means for creating relative movement between the same, saidsets of electrodes be.'-

ing so constructed and arranged that the gaps between the same are practically closed and said circuit rendered substantially metallic' ally-continuous in .an interval ci time after the 'first discharge of the condenser in said circuit shorter thanv the duration of the effective radiation of energy from said\circuit. S. A circuit-controller serially connected 4. A circuitecontroller iserially'connected' 'of said circuit.

9. A circuit-controller having a plurality of sets of serially -subdivided electrodes, means for creating relative movement between the same, and a circuit including a i source of constant potential and an inductance in series with said circuit-controller.

. 10. A circuit-controller having a plurality of constant potential andan inductance in.

series with said circuit-controller7 and a condenser in shunt thereto, said sets of electrodes being so constructed and "arranged that 'said circuit is opened s uiiciently to withstand the maximum potential to which said4 condenser is charged with-in a .timeI of the circuit including said inductance and i said condenser.

12. A circuit-controller having a plurality of sets of vseriallysubdivided electrodes,

means for creating relative-movement between the same, acircuit including a source of constant potential andan inductance in is opened suiciently towithstand the maxi-- vmum potential to which said condenser is 'charged' within a time shorter Vthan oncuarter kof 'th'egtim'e period of the circuit inc uding said condenser and inductances, and so that thesaid sonorous circuit is practicallv closed and renderedA substantially metallically continuous in an interval of time after the first desired discharge of the condenser in said sonorous circuit comparable. with the time period of said sonorous circuit.

13. Acircuit-controller having a set oi' serially-subdivided electrodes and two sets of alternate serially subdivided electrodes connected in multiple, a circuit including a :souifee of constant potential and an induetiipheiy, und ineens foi' changing the dist-nee ence in series with said eiieuit-eontl'oller, between said eleetrodes so es te alter the und ineens for ehenging the distance beratio of tinie during wnieh the circuit through tween seid sets oi' elteinete'eleeti'odes. f i said controller is open to the tiineduring 14. A eiieuiteeontl'oller comprising a rotor I which it is closed. j h-.wing its periphery divided into conducting In testimony whereof, I have hereunto subund insulating sections, :t circuit including. a scribed my naine this 9th dey oi' Nov. 1908 soul-ee oi' constant potential and an induet- SEVALL CABOT. ence in series with said circuit-controller, Witnesses:

o a plurality ol' serially-subdivided electrodes ARTHUR W. CALVnR,

arranged to ineke Contact with Said pe- GEO. K. Woonwon'rrr.

It is hereby certified that in Letters Patent No. 917,749, granted April 13, 1909, upon the application of Sewell Cabot, of Brookline, Massaehusetts, for an improvement in Ciremit-Controllers,.errors eppear in the printed speeieation requiring correction, es follows: n page'3, line 128, equation (lg), the vletter P shonld read p; page 4, line 85,.equetion (i), the letter M shouldn-eed m, and same page, line loheqruation (n1), i2 should read i2; and that the Said Letters Patent should be read with theseveorreetions therein that the seme may conform to the record of the euse in the Patent Oliee.

Signed and sealed this 4th day of May, A. D., 1909.

[SEAL] C. C. BILLINGS. 

